Pancreatic cancer is a deadly disease that is typically refractory to even the most aggressive cytotoxic chemotherapy regimens. Recent advances in chemotherapy for pancreatic cancer have led to some improvement in response rates; however, the majority of patients still do not substantially benefit from therapy. Responses to chemotherapy commonly occur through apoptosis, a form of programmed cell death. Our goal is to identify genes whose loss of function enhances sensitivity of pancreatic cancer cells to apoptosis. BH3 profiling is a well-characterized upstream measurement of the apoptotic sensitivity or priming of cancer cells and has been shown to correlate with response to chemotherapy and disease prognosis in certain cancer types. We will utilize a novel screening approach called RNAi-BH3 Screening (RiB Screening) that combines loss-of-function genetic screening using pooled lentivirally delivered shRNAs with the technology of BH3 profiling. In this approach, we will identify genes whose knockdown results in enhanced priming for apoptosis across several pancreatic cell lines. Based on this loss of function genetic screen, we will attempt to identify known small molecules targeting these genes, and determine whether they alter apoptotic priming and chemosensitivity. Finally, we propose to evaluate potential clinical utility of identified genes or small molecules by determining their effect on BH3 Profiles and chemosensitivity in fresh patient-derived pancreatic cancer samples. The successful identification of such genes and small molecules will not only improve our understanding of chemotherapeutic response, but could also serve as novel biomarkers or therapeutic targets.